Usb-to-uart bridge – Xilinx SP605 User Manual

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SP605 Hardware User Guide

UG526 (v1.8) September 24, 2012

Chapter 1: SP605 Evaluation Board

12. USB-to-UART Bridge

The SP605 contains a Silicon Labs CP2103GM USB-to-UART bridge device (U4) which
allows connection to a host computer with a USB cable. The USB cable is supplied in this
evaluation kit (Type A end to host computer, Type Mini-B end to SP605 connector J23).

Table 1-16

details the SP605 J23 pinout.

Xilinx UART IP is expected to be implemented in the FPGA fabric (for instance, Xilinx XPS
UART Lite). The FPGA supports the USB-to-UART bridge using four signal pins: Transmit
(TX), Receive (RX), Request to Send (RTS), and Clear to Send (CTS).

Silicon Labs provides royalty-free Virtual COM Port (VCP) drivers which permit the
CP2103GM USB-to-UART bridge to appear as a COM port to host computer
communications application software (for example, HyperTerm or TeraTerm). The VCP
device driver must be installed on the host PC prior to establishing communications with
the SP605. Refer to the evaluation kit Getting Started Guide for driver installation
instructions.

References

Refer to the

Silicon Labs

website for technical information on the CP2103GM and the VCP

drivers.

In addition, see some of the Xilinx UART IP specifications at:

http://www.xilinx.com/support/documentation/ip_documentation/xps_uartlite.pdf

http://www.xilinx.com/support/documentation/ip_documentation/xps_uart16550.pdf

Table 1-16:

USB Type B Pin Assignments and Signal Definitions

USB Connector

Pin

Signal Name

Description

1

VBUS

+5V from host system (not used)

2

USB_DATA_N

Bidirectional differential serial data (N-side)

3

USB_DATA_P

Bidirectional differential serial data (P-side)

4

GROUND

Signal ground

Table 1-17:

USB-to-UART Connections

U1 FPGA Pin

UART Function

in FPGA

Schematic Net

Name

U30 CP2103GM

Pin

UART Function

in CP2103GM

F18

RTS, output

USB_1_CTS

22

CTS, input

F19

CTS, input

USB_1_RTS

23

RTS, output

B21

TX, data out

USB_1_RX

24

RXD, data in

H17

RX, data in

USB_1_TX

25

TXD, data out

Notes:

1. The schematic net names correspond with the CP2103GM pin names and functions, and the UART IP

in the FPGA must be connected accordingly.

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